形状特征的定义

A Novel Definition of Form Feature

本文研究形状特征的形式定义，并强调了形状特征的非几何语义，引入面邻接图ＡＡＧ和几何约束集来定义特征体素，使形状特征的空间属性和边界局性结合起来，从而面向基于约束的设计。最后，作者尝试用代数规格说明来定义特征，并给出了实例。

Being an essential concept in CAD/CAM and even in Concurrent Engineering, feature is the theoretical basis of related technology, but formal defination of it is still wanted. On the basis of existing literature, this paper define form feature as' three-tuple aggregation (G, D, S) relevant to the whole artifact or a part of it, where G, D, S are knowledge of geometry,manufacturing-domain (CIM domain) and a specific stage of product life cycle CLM stage), respectivety. These knowledge with aggregation and creating rules can be used for design, recognition and .classification'. In this defination,non--geometric semantics of form feature are emphasize d, and featured-primitive,as feature constructors, are defined by augmented adjacency graph (AAG) and geometric constrains. Consequently, tie volumetric and boundary propertiescan be unified, and constraint -based design paradigm introduced. Finally, algebraic specification is utilized to represent form feature definition , with examples given.